1. Field of the Invention
The invention relates to a metallic sleeve for bridging a leakage point on a pipe or tube, wherein the sleeve can be placed on the inner wall surface of the pipe with the aid of an expansion technique.
2. Description of the Related Art
Such a sleeve is known from Published European Application No. 00 47 407. In that publication, the sleeve has partial regions provided with toothing near its top and bottom ends. After the toothing has penetrated into the pipe wall in a first stage by hydraulic expansion of the regions, the region located between the toothings is likewise hydraulically expanded in a second stage. A shrinking process which thereby occurs in the axial direction is intended to reinforce the connection between the pipe and the sleeve in the vicinity of the toothing. Due to the different elastic resilience of the deformed materials which depends, inter alia, on the different deformation paths of the pipe and the sleeve, a gap of approximately 5 to 10 sm occurs between the pipe and the sleeve during the expansion process. Therefore, small quantities of leakage have to be tolerated. If the leakage is to be suppressed completely, the sleeve ends have previously been required to be welded to the pipe.
The welding constitutes a heat treatment which can lead to undesired stresses, and moreover increases the time spent on pipe repairs. Furthermore, the formation of corrosion in the gap cannot be assessed.
A device for reconstructing spigot-and-socket joint piping is also known from the German journal gwf-Gas/Erdgas (1975), No. 10, pages 412 to 417. In that publication, the leaking point in the region of the spigot-and-socket joint is sealed with the aid of an adhesive-coated aluminum backing foil. By using an inflatable diaphragm, the aluminum foil is brought into contact with the inside wall of the pipe until adhesive bonding has been achieved. The use of adhesive permits the known method to be used only in those cases where the adhesive is not attacked by the medium flowing in the piping.